Wales' NHS will collapse unless changes are made to the way treatments are delivered, the First Minister has warned.

Carwyn Jones said that reorganisation of the health service was necessary to ensure that the care and services provided to the people of Wales is safe and sustainable in the future.

His comments come as health boards across Wales put together and finalise their plans for hospital services.

The controversial changes are based on moving some services into the community while others could be centralised in larger hospitals within health board regions.

Mr Jones said he believed the changes would improve the NHS and were required to prevent the health service from falling under the strain of increased demand from an ageing population with rising levels of chronic disease.

Speaking to the BBC’s Sunday Politics programme, he said: “It would collapse otherwise – there’s no question of it. The worst thing that can possibly happen is that nothing happens and then we see services just disappearing at random all over the place. People would say ‘well hang on a second, you knew this was happening, why didn’t you do anything?’ That’s far, far worse.”

When asked if he believed the Labour party would pay a “political price” for the changes being made, Mr Jones said: “No, I don’t believe we will, because I think that people will see what we’re trying to do is have a safe and sustainable health service.

“There is no getting away from the fact that there has to be change in the health service to be safe in the future. I’m not going to sit here as First Minister and say let’s do nothing at all and it does not matter if it’s safe or not. I’m not going to do that while I am in this job.”

Currently, two of the seven health boards – Betsi Cadwaladr and Hywel Dda – have voted on what changes will be made while combined plans by health boards across the south of the country under the South Wales Programme will be put to public consultation in the coming weeks.

One of the most controversial decisions by Betsi Cadwaladr University Health Board is to move level three neonatal care across the border to Arrowe Park on the Wirral.

The board’s decision has prompted three of Wales’ top medical organisations, the British Medical Association, the Royal College of Nursing and the Royal College of Midwives, to take the unprecedented move to come together to oppose the plans.

Mr Jones said he could not comment on specific proposals in case they are referred to the Welsh Government by the Community Health Council, but said it would always be the case that some services in England would be used by Welsh patients.

He said: “Generally there will always be services delivered in England that will be available to people in Wales. We can’t replicate the entire British NHS here in Wales.

“The NHS is important to Wales, of course we understand that, but we never said we were going to create an entirely self-contained NHS here in Wales. That’s never been our intention. It’s about ensuring that we have safe and sustainable services that are available to the people of Wales.”

His comments echo recent warnings by the Royal College of Physicians, who said the NHS was “on the edge” and patients would come to harm if changes were not made.

Dr Richard Moore, a consultant at the University Hospital of Wales, Cardiff, said: “There is no doubt that this is a time for change and there’s a need for change. Hospitals in Wales are on the edge.

“To stay where we are is not good enough. Patients will come to harm – they are coming to harm.”

The First Minister’s warning comes as a survey published by the Nursing Times found that more than half (57%) of nurses think their ward or unit is dangerously understaffed.

More than three quarters (76%) said they had witnessed “poor” care in their ward or unit over the past year – of which nearly 30% said they see poor care regularly.

A majority of respondents said the ratio of patients to each nurse at their hospitals could compromise patient care.

More than eight out of 10 respondents said staffing on general medical wards in an acute hospital was at a ratio of eight patients to one nurse, or more.

And of these nearly half (44%) said the ratio was 10 or more patients per nurse.

A ratio of eight or more patients per registered nurse is associated with patient care on a ward regularly being compromised by short staffing, according to the Royal College of Nursing (RCN).

RCN Wales’ director, Tina Donnelly, has repeatedly said that nurses want to provide high levels of care, but due to poor staffing, they were often put in a position where they were unable to do so.

She said: “Nurses have told us that the system is under immense pressure and about short staffing levels.

“It comes across as lacking compassion but what they lack is sufficient resources. I actually think managers are in a very difficult position as well and they are being asked to provide an increased level of output while savings millions of pounds at a time patients are more acutely ill.”

Health Minister Lesley Griffiths has previously said that she expects Health Boards to have the right levels of staff to ensure dignity and care for patients.